The effect of cationic polymer treatment on dye staining and on the adhesion of charged particles to dentin.

Objective: The aim of this study is to examine the influence of electrostatics in determining the ability of charged material to adhere to dentin surfaces.
Design: Deep dentin slices were obtained from third molars. In one set of experiments the effect of a cationic polymer (polyquaternium-6) application on dentin staining with the cationic dye (toluidine blue) was assessed using a colour analyser and photography. In other experiments the effect of cationic polymer treatment on adhesion of cationic and acidic anionic 0.5 microm latex beads was assessed using scanning electron microscopy and quantification of dentin surface bead attachment. In both experiments dentin discs were split in half and the effect of cationic polymer was compared to water treatment.
Results: Water-treated dentin was stained an intense blue after application of toluidine blue. Cationic polymer pretreatment significantly reduced the intensity of dye staining. SEM examination of dentin treated with cationic beads showed a dense coverage of beads. In contrast, dentin that was pretreated with cationic polymer was virtually free of cationic beads. Acidic anionic bead treatment left a coating of beads on the dentin surface. Pretreatment with the cationic polymer prior to anionic bead application caused a significant reduction in bead coverage.
Conclusions: Dentin treatment with a cationic polymer inhibits the staining of dentin by cationic dye and adherence of cationic beads. Acid functional anionic beads adhere to the dentin surface but the pattern of adherence is altered by cationic polymer application. Electrostatic forces may influence the attachment of therapeutic materials to dentin surfaces.
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